Lithium Conversion Issues

kometose · April 10

Hello. After reading a number of posts online and in this forum, when my original battery started to die on my 2015 320cs, I decided to switch to a Chins 100w Lithium. From what I had read it should be a clean swap sans the fact that the older converter wouldn’t charge to a full 100%, which I was fine with (it charges to around 90-95% though).

Also have folding solar panels to help top off.

I moved the battery location to inside under the bench with the rest of the electrical. Just ran 10g wires from the tub, under the trailer and up into the bench so wiring should be correct.

Having an issue where the battery does fine and will remain charged for days or weeks, but then suddenly drops all charge to zero (like over the course of an hr or two). I’ve tried all sorts of tests, and installed a battery cutoff and seems to be fine when I disconnect the battery from the rest of the system.

Any thoughts on what to check?

part 2: finally decided to just take it into a local RV service place and they said it needs a new converter to fix this issue. I’m skeptical that that will solve it. They also quoted me nearly $900. I know the part is around $270. That just seems high to me. Anyone know if the swap would require that much labor time? And is it something I could just swap myself with the new part? I’m pretty handy with most things and have a general understanding of wiring.

Thanks in advance!

Grumpy_G · April 10

A new converter will not fix that issue. LiFePo batteries have a battery management system that turns the output off when the charge gets low. It's normal to see almost no voltage change and then the output turns off. That's why most people use a battery monitor to keep track of how much of the capacity has been pulled out of the battery so they don't get surprised when the battery turns off.

kometose · April 10

Thanks for the response! The Chins battery has a built in BMS app which is what Im checking the charge with. It will be an expected say, 78% for example and over the course of a day steadily go down to 72% that eve, then 68% the next morning, then suddenly, no juice and BMS reads 0%.

kometose · April 10

How low does a LiFePo battery go before it auto shuts off? My understanding is you can run them quite a bit lower than my example above (like 55%-70%) which is an advantage over the standard marine battery?

elbolillo · April 10

Each battery manufacturer will have their own limit for when the BMS will shut the battery down. Lifepo batteries should be able to be discharged close to their full capacity. Again, that will vary among brands.

My suspicion is that something is amiss with the BMS in your battery. Are you certain that there is nothing connected that is drawing down the battery?

Grumpy_G · April 10

Agree with @elbolillo that the BMS might be out of whack. I'm not familiar with the specifics of the Chins one but I'd venture it needs a "full cycle" to accurately gauge the battery status. Percentages are somewhat murky, does the app show Ah or Wh consumed ? The battery should deliver 100Ah or 1280Wh, or very close to it.

One quirk with LiFePo is that they like to see a higher charging voltage. The higher voltage allows the BMS to balance the cells. That's why there are specific chargers, but you don't necessarily need a new converter. You can also use a LiFePo capable external charger, or the solar panels if the controller has a LiFePo setting. Personally I use the standard converter for bulk charging and then solar for the last few Ah.

pthomas745 · April 10

The biggest cause of lithium battery failures is the failure of the BMS.

rfuss928 · April 10

kometose said:

I moved the battery location to inside under the bench with the rest of the electrical. Just ran 10g wires from the tub, under the trailer and up into the bench so wiring should be correct.

Your battery leads run nearly 20 feet from you battery all the way to the front tub then back to the converter right in the same cabinet . That is very long battery wiring with lots of voltage loss at high current even if you had the correct converter with an appropriate charge process. It would be quite easy to run a short pair of 8 or 10 awg directly to the converter battery connections now that you battery is so close.
Your battery needs to be brought up to a full charge with 14.4 -14.6 volts bulk and allowed to rebalance with an absorption at ~13.6-13.8 volts for at least a couple hours. My Li batteries would not fully charge until I raised the Victron default Li charge bulk setting from 14.2 to 14.4.
IMO - Until the battery is properly fully charged with lithium specific charger it will be very hard to diagnose the root cause of your battery problems.

kometose · April 11

Thank you so much, all! This has been driving me crazy and I now feel like I’m on a path to solving. I’ll order a Li battery charger right now and get the battery charged fully to 100%.

Currently, my BMS has balancing set to “off” and protection set to “off”. Should either of those be turned to “on”? I need to do some reading on this particular chins battery and the BMS to get more familiar.

I’ll also plan to rewire the battery with shorter 10g wires to reduce the voltage loss.

I may have more questions as I go but so grateful for the assurance thus far!

kometose · April 11

Oh, one more question now that I think about it, should I just save my $ on the Li charger and instead purchase the updated converter that works with LiFePo? I was quoted a price of $270 for that (WFCO/Arterra 04-0887). Can I install it? Just wires from old one into slots in new one?

rfuss928 · April 11

The new converter is probably necessary long term and will avoid the necessity of a separate Li charger.
If you can handle the battery rewire the converter swap should be manageable. The AC breakers are difficult just because of many stiff solid core 12awg wires in a small space. Label the wires color (DC) or breaker number (AC) and they should match up. You'll have to put the proper fuses in the DC circuits...
Have fun?
Bob

SLJ · April 11

I'd forget swapping to an auto detect WFCO converter. Bad design and a big hassle getting it to "auto detect" for a lot of people. A Victron smart charger is much better quality. Leave the WFCO you have in to run the shore power and supply DC when plugged in.

elbolillo · April 11

When we had our ‘21 Tab 320 I had 200ah of LiFiPo4 batteries and didn’t bother swapping out the converter. With a good day of sunshine I could fully charge the batteries and allow for sufficient absorption charge time to correctly balance the two batteries. When there wasn’t enough sunshine and I needed to get the batteries topped off for a trip I would use a Victron Energy blue smart 12-Volt 15 amp battery charger. I had the dongle hardwired into the battery bank and would just connect the charger to get everything up to 100%. I always switched the converter function off on the WFCO since it wasn’t a model that supported charging lithium batteries.

kometose · April 11

Thanks much! Is this the Victron you're using? https://a.co/d/hpxEAc7. What do you mean by "dongle hardwired into the battery bank"? Is the dongle part of the Victron charger? Or, because I just have the singe battery, would I just permanently attach + and - to the battery poles? And, finally, does the converter have a simple on/off switch? Or how do you turn that function off? Thanks in advance for your patience in walking me through this.

kometose · April 11

Also, as I'm diagnosing things with the BMS, this is my current screen on the app. If anyone sees anything amiss, please let me know. Looks like the 4 cells are very close to balanced. And, as above, should Balance and Protection be set to "off"?

elbolillo · April 11

kometose said:

Thanks much! Is this the Victron you're using? https://a.co/d/hpxEAc7. What do you mean by "dongle hardwired into the battery bank"? Is the dongle part of the Victron charger? Or, because I just have the singe battery, would I just permanently attach + and - to the battery poles? And, finally, does the converter have a simple on/off switch? Or how do you turn that function off? Thanks in advance for your patience in walking me through this.

https://www.amazon.com/gp/product/B07DWJD84N/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

This is the one that I purchased. It comes with M8 eyelets that you can connect to your battery. I used battery bank because I had two 100ah batteries connected together.

Image: https://us.v-cdn.net/5021717/uploads/editor/kw/2pr2ffufwbx5.png

Grumpy_G · April 11

kometose said:

And, as above, should Balance and Protection be set to "off"?

The specific screen shows the state of the battery, charging and discharging enabled, not currently balancing and protection not triggered. On the control screen it should show "Autobalance" or similar which means the BMS will balance the cells if needed. As you said, the cells are well balanced within 0.001V.

Yoshi_TAB · April 11

kometose said:

And, finally, does the converter have a simple on/off switch? Or how do you turn that function off?

Hi,

The converter does not have an on/off switch. A common approach to create one is to split the last branch #5, from a single circuit breaker into a tandem 2 circuit breaker. The OEM converter/charger is usually wired into branch #1 (on a newer 320). You bring that AC wire over to one of the circuits on the tandem breaker. You are then able to turn off the charger/converter with the breaker ON/OFF switch.

elbolillo · April 11

Yoshi_TAB said:

kometose said:

And, finally, does the converter have a simple on/off switch? Or how do you turn that function off?

Hi,

The converter does not have an on/off switch. A common approach to create one is to split the last branch #5, from a single circuit breaker into a tandem 2 circuit breaker. The OEM converter/charger is usually wired into branch #1 (on a newer 320). You bring that AC wire over to one of the circuits on the tandem breaker. You are then able to turn off the charger/converter with the breaker ON/OFF switch.

Precisely what I did.

bergger · April 12

Would you turn the converter off when you were plugged into shore power? If so, why? It is my understanding that the converter won't hurt the batteries but just not fully charge them. Solar should finish the job and like mentioned above, a proper auxiliary charger can do the job when solar can't. I guess I just don't understand when and why you would turn off the converter. Thanks for entertaining my ignorance.

Yoshi_TAB · April 12

bergger said:

Would you turn the converter off when you were plugged into shore power? If so, why? It is my understanding that the converter won't hurt the batteries but just not fully charge them.

Hi, Others can chime in, but I agree there is no reason to turn it off (in most cases).

In my case, I have an inverter with a transfer switch that puts AC power to everything in the trailer when on battery power. When the inverter is on, if there is not a way to turn off the charger, you end up in a loop where battery power is now powering the battery charger and charging itself, the battery (if that makes sense). To avoid this condition, you need a means to turn off the charger. I actually did not do as I suggested above, but wired my charger into the transfer switch so its only powered when on shore power via a relay in the transfer switch.

I have a different experience with my non lithium WFCO charger than most. I find when on shore power, the charger rarely kicks on and sends any current to the batteries to charge them. I can fanagle it on by turning turning the main breaker on /off, when it does begin to charge, it will fully charge my batteries consistently to 100% but extremely slow. I have gone to a stand alone Victron charger, but did not disconnect my WFCO charger.

elbolillo · April 12

@bergger Like @Yoshi_TAB I had installed an inverter in my Tab 320. I installed a double breaker to allow me to turn off the converter when using the inverter. Most times I just left the converter off since the vast majority of our travel was without shore power.

kometose · April 22

Just to post a followup as to where things are in case it's helpful for someone else, I purchased the above mentioned Victron Li charger and let it fully charge the battery and allowed for plenty of absorption time (hours). I then did some tests and for a week—turning on the roof vent fan and a few lights all day for 6 days straight (turned off at night), and the battery drained predictably as it should have (9-12% per day) until it reached around 27% according to the BMS. It never behaved as it had before with a sudden drop to 0%. Good deal!

I then, again, charged it back to 100% with the Victron Li charger, but noticed the BMS showed 100% long before the Victron completed its bulk cycle etc.

So, at this point, I believe the issue is indeed, as many stated above, that the BMS is "out of whack" and that the battery wasn't suddenly discharging from 64% to 0% (for example) as I thought, but rather was probably never fully charged and was probably actually only 15% (or something) charged when the BMS showed 64%, and the battery just ran out, giving the appearance of a sudden drop from 64% to 0%.

Anyway, still doing some further testing and anxious to try it on the next trip, but feeling pretty confident that was/is the issue. Thanks a ton to all who weighed in on my issue, and glad I didn't pay $900 for a new converter which clearly would not have fixed the issue.

Last question: could I now just install the Victron Li charger under the bench near the LiFePo battery, screw down the pos-neg leads to the battery, and then just plug the cord into an empty AC electrical socket (a 2 gang outlet that it appears the water heater is plugged into) there? I'm thinking with this, when we plug into shore power, it will fire up the Victron to "top off" the battery. OR, will this conflict with the converter at all or cause some dangerous electrical feedback loop or conflict? Thanks.

SLJ · April 25

I switch my batteries off when plugged into shore power and just turn on my Victron smart charger to charge the batteries if needed and let the WFCO converter supply 12 volts to the camper. When I unplug from shore power I flip the batteries back on.

AnOldUR · April 25

I do the same as @SLJ. I also turn off solar charging when the Victron Energy Blue Smart IP22 is plugged in. I doubt that the WFCO or solar would have any conflicts with the Victron charger, so this may not be necessary?

Yoshi_TAB · April 25

Hi,

What is reason to turn off the solar and/or batteries when using the IP22?

Thank you

AnOldUR · April 25

@Yoshi_TAB It may be misguided, but my thought is to not confuse the IP22 with other incoming voltage and have it not go through the proper sequence from bulk to storage mode. All the devices are networked, so this may not be necessary, but the 30 amps from the IP22 is fast enough for most situations. If I was in a rush to get the batteries charged, I'd try using all three sources and monitor the mode of the IP22, but that situation hasn't come up yet.

Howdy, Stranger!

Quick Links

Categories

Lithium Conversion Issues

Comments